Quantitative Determination of Sugars in Food by Gas Liquid Chromatography of Trimethylsilyl Derivatives

Abstract

Gas liquid chromatography was employed as a means to determine the amount of various sugars in food.
The procedure which was newly established here was as follows;
1) Preparation of the sample
2) Extraction of sugars
The sugars were extracted with water or with 80% ethanol by reflux heating for 15min.
3) Oximation
One ml of hydroxylamine hydrochloride in pyridine (25mg/ml) was added and the mixture was heated at 70∼80°C for 30min
4) Trimethylsilylation
Two point five ml (2.5ml) of pyridine/hexamethyldisilazane/trimethylchlorosilane (10/2/1) was added. After the solution was allowed to stand at room temperature for 5min., it was centrifuged at 3, 000r.p.m. for 10min.
5) Injection into GLC
Oxim-trimethylsilyl (Oxim-TMS) derivatives were separated on OV-17 by a combination of isothermal and programmed oven temperatures. Sorbitol, fructose, glucose, sucrose, lactose and maltose were measured with inositol or n-docosane as the internal standard for a single chromatogram. The method was judged satisfactory as it was reliable and reproducible.
Oxim-TMS derivatives can be kept for one week, if they are kept in capped glass tubes at room temperature. Water extracts can be kept for 25 days at either 4°C or -20°C.